When a truck barreled through Las Ramblas, the beloved pedestrian walkway in central Barcelona, killing at least 14 and injuring dozens more, the so-called "Islamic State" (IS) was quick to claim responsibility. Earlier in the year the terrorist group had threatened to attack popular tourist destinations in Spain. They have possibly delivered their promise with Thursday evening's attack, in which most of the victims were tourists.

Read more: Merkel : Barcelona terrorists showed 'contempt for humanity'

Did Spanish officials suspect anything?

One day before the attacks, commuters met with unusually intense security measures on the highway heading south. César Martinez and his family were among those who witnessed the scene: "Armed units stopped us on the A7 by Malaga. We were treated like criminals and had the feeling that something bad had happened. But it ended up happening a day later."

Did the police near Malaga that day know something? Following the attack, a 28-year-old Moroccan and a person who came from the Spanish autonomous city of Ceuta were apprehended. Their arrests put another aspect into focus: the growing immigration from Morocco to the Spanish coast, and the tensions in the autonomous cities of Ceuta and Melilla that have been rising as a result.

The Spanish and Moroccan intelligence services work closely together, at least at the intergovernmental level. Madrid has also agreed to additional economic arrangements with Rabat in order to help stem the flow of migrants, but since a crackdown on immigration in nearby Libya, there has been increased pressure on Morocco. Hundreds of refugees are stranded daily in the southern region of Andalusia, not far from the tourists who visit there to enjoy the sun and sand.

Show of strength in Catalonia

What seems to have become clear since Thursday's attacks is that Catalonia has a security problem, something the Catalonian newspaper El Periodico has pointed out several times in the past year. The autonomous region has, much like the Basque Country, its own police force, the "Mossos d'Esquadra," or "Mossos." It also has its own counterterrorism unit, which theoretically is controlled by Madrid. According to media reports, however, the unit hasn't been under the direction of the Spanish state for months. For many, the message is clear: Without Spain, Catalonia isn't safe. And that was also the message from the spokesperson for the ruling People's Party (PP), Rafael Hernando, during a television address on Friday: "What we need today is the experience of the Spanish state in the fight against terrorism."

This declaration has a clear double meaning: "Don't fear, we're here for you" and "Catalonia needs Spain." Of course, this message must be read in the context of Catalonia's burgeoning independence movement. On September 11 the National Day of Catalonia will be celebrated, and on October 1 a referendum has been organized for the region's independence - the second in Catalonian history. It is illegal under the Spanish constitution and has already led for the first time in three years to the arrest of a politician. Hernando hopes "that the police units will now work together and that this fight will be led by Spain, as it should be."

Independence on the shelf

Even as the number of the dead is still in question, a bitter fight is already beginning among the authorities as to whom is to blame for the attacks. Spanish Prime Minister Mariano Rajoy craftily used the moment to travel to Barcelona and call for national unity and cohesion. He had no Plan B for the possible independence of Catalonia, but now he can count on the fact that these efforts by the regional government will be suspended as attention shifts toward preventing another such attack.

Rajoy is proving his political instincts and has already announced that the national anti-terror unit - the largest in Europe due to the decades-long fight against the Basque separatist group ETA - will coordinate the investigations and further security measures for the region. "We have already won many fights against terrorism, and we Spaniards will win this one too," Rajoy said. The public still has yet to hear a response from the "Mossos."